AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Air Intake Filter Media Loading by Solid and Oil Mixtures
QISHENG OU, David Y. H. Pui, University of Minnesota
Abstract Number: 457 Working Group: Control and Mitigation Technology
Abstract Current air filter test standards employ pure solid (ISO dust, carbon black, cotton linter, KCl, etc.) or pure oil (DEHS) as testing aerosols. Only pure solid particles are used to assess the filter holding capacity or to condition the filter in test standards. Filters used in field may face aerosols with different physical states, e.g. mixtures of solid and liquid (oil) particles for filters used for colloid/mist removal, including cooking or oil handling application, offshore oil drilling platform, and etc. Although the clean filter efficiency may not be affected much by aerosol physical state, the filter loading and clogging behaviors could be different.
In this study, particle loading and clogging behaviors on three types of air intake filter media (cellulose, cellulose with nanofiber coating on top, and ePTFE) were tested using solid and oil mixtures. Two types of solid particles were generated: sodium chloride and soot agglomerates. The solid fraction was mixed with oil particles generated from another Collison-type atomizer, in which DEHS or a series of high-viscosity PAO oil particles were generated. The solid and oil particle mixtures were loaded onto a 57-mm diameter flat filter media with controlled mixing ratio varying from pure solid to pure oil with 10% increment. The holding capacity of cellulose media is found to increase with increasing oil fraction in the mixture; while the clogging on nanofiber or ePTFE switches between two patterns. At high solid fractions, solid-oil mixtures deposit on the surface of media, forming cake, which leads to higher holding capacities than conventional cellulose media. At high oil fractions, solid-oil mixtures form a paste-like thin film, which spreads out and coats on top surface of fine fiber layer in nanofiber or PTFE media, resulting in faster clogging and reduced holding capacities than cellulose media.